LED traffic light FAQ. Here are a number of frequently asked questions concerning retrofitting street lights with LEDs. For full information see LED.

What does an LED traffic light look like? An LED traffic light looks very similar to a regular traffic light. It still gets the job done and is actually brighter. An LED is actually very small and therefore the traffic light is made up of a bunch of smaller lights, this is apparent when you look closely. The color of the light depends on the exact composition inside the bulb. Who Invented the LED? It all began when Oleg Vladimirovich created the first LED in 1927. There was no practical use for it until 1962 when it was discovered that the infrared LED could be changed into a visible red LED. How does an LED work? An LED is basically a tiny light bulb with a semiconductor diode in place of a filament. Inside the diode, there are positively and negatively charged areas. When a voltage is applied to the diode with the positive end hooked up to the negative area and the negative end hooked up to the positive area the electrons inside become excited and jump from the positively charged to negatively charged areas. This interaction produces light. What is a diode? A diode is a component that restricts the directional flow of charge carriers. Also a diode allows an electric current to flow in one direction, but blocks it in the opposite direction.

An alternative or natural building involves a range of building systems and materials that place major emphasis on sustainability. Ways of achieving sustainability through natural building focus on durability and the use of minimally processed, plentiful or renewable resources, as well as those that, while recycled or salvaged, produce healthy living environments and maintain indoor air quality. Natural building tends to rely on human labor, more than technology. As Michael G. Smith observes, it depends on "local ecology, geology and climate; on the character of the particular building site, and on the needs and personalities of the builders and users."

The basis of natural building is the need to lessen the environmental impact of buildings and other supporting systems, without sacrificing comfort, health or aesthetics. To be more sustainable, natural building uses primarily abundantly available, renewable, reused or recycled materials. The use of rapidly renewable materials is increasingly a focus. In addition to relying on natural building materials, the emphasis on the architectural design is heightened. The orientation of a building, the utilization of local climate and site conditions, the emphasis on natural ventilation through design, fundamentally lessen operational costs and positively impact the environmental. Building compactly and minimizing the ecological footprint is common, as are on-site handling of energy acquisition, on-site water capture, alternate sewage treatment and water reuse.